Colon and rectal carcinoma.

In the United States the incidence of carcinoma of the colon or rectum appears to be increasing. Although certain dietary habits appear to be associated with disease incidence, the putative carcinogens in the lumen of the bowel remain unidentified. The use of clinical screening based on a combination of proctosigmoidoscopy and tests for occult fecal blood allows detection of colorectal carcinomas at an early stage; however, it is unclear whether such screening is cost-effective in persons over 40 years of age or if treatment undertaken on the basis of screening results truly alters the natural history of the disease. Surgical resection is the mainstay of curative therapy, and its effectiveness will probably be enhanced by adjuvant x-ray therapy and chemotherapy.